Saranyu and Erinys: related... but how?

Saranyu (aka Saranya) was a minor Vedic goddess, linked to dawn, dusk, shadow and night. Turned into a mare, she was impregnated by Vivasvat (or Surya, the sun-god), begetting the Twin Gods.
Erinys, a kind of female monster in Greek mythology. It's also the epithet of Demeter when, furious, turned herself into a mare, and begot the flying horse Arion (Poseidon was the father).

Saranyu and Erinys were obviously related, but the common source was not necessarily PIE.
If there's a common PIE for their names, what would it be? Cognate goddesses were Medousa/Gorgo:, Podarge/Harpyia, Macha/Mórrigáin/Medb, maybe Nordic Angrboda or Jarnsaxa.

Saranyu and Erinys don't show a "regular" correspondence, probably the original names suffered some irregular shift.

Saranyu: and Erinys points to a PIE ending *u: < *-uh2

Erinys < *Erinu:- or Erinyu: or *Erunu:- or *Erunyu:

E- < *h1 or just a prothetic vowel ?
Sa- and E- were cognates, *Erinu: < *HerHinu: ?

Saranyu: would point to a PIE *-nyu: or it's just the coalescence of *-ni:/-nya: and -nu: ?

Erinus < *HerHu-nu: or *HerHu-ni: < **SerHu-nu: or *SerHu-ni: or *SerH-nyu:
Saranyu < *Sarani: or *Saranu:

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